Cleaner head

ABSTRACT

A cleaner head for a vacuum cleaning appliance includes a suction cavity having a downwardly-directed opening through which debris enters the suction cavity. The opening is bounded in part by a front edge and a rear edge which is substantially co-planar with the front edge. A thread lifting strip is mounted on a support located within and moveable relative to the suction cavity. A spring urges the support in a direction extending towards the opening.

REFERENCE TO RELATED APPLICATIONS

This application claims the priority of United Kingdom Application No.1119946.0, filed Nov. 18, 2011, and United Kingdom Application No.1217703.6, filed Oct. 3, 2012, the entire contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a cleaner head for a cleaningappliance. In a preferred embodiment, the cleaner head is suitable foruse with a vacuum cleaning appliance.

BACKGROUND OF THE INVENTION

A vacuum cleaner typically comprises a main body containing dirt anddust separating apparatus, a cleaner head connected to the main body andhaving a suction opening, and a motor-driven fan unit for drawingdirt-bearing air through the suction opening and the cleaner head, andinto the main body. The suction opening is directed downwardly to facethe floor surface to be cleaned. The dirt-bearing air is conveyed to theseparating apparatus so that dirt and dust can be separated from the airbefore the air is expelled to the atmosphere. The separating apparatuscan take the form of a filter, a filter bag or a cyclonic arrangement.

Vacuum cleaners generally include cylinder, or canister, cleaners,upright cleaners and hand-held cleaners. A cylinder vacuum cleanerincludes a main body supported by a set of wheels which is dragged alonga floor surface by a hose and wand assembly extending between the mainbody and the cleaner head. The cleaner head is generally releasablyattached to the end of the wand which is remote from the main body. Inuse, a user pushes and pulls the wand to move the cleaner head forwardsand backwards over the floor surface. An upright vacuum cleanertypically comprises a main body, a rolling assembly mounted on the mainbody for manoeuvring the vacuum cleaner over a floor surface to becleaned, and a cleaner head mounted on the main body. In use, a userreclines the main body of the upright vacuum cleaner towards the floorsurface, and then sequentially pushes and pulls a handle which isattached to the main body to manoeuvre the vacuum cleaner over the floorsurface.

A cleaner head may be provided with one or more of a number of featuresfor improving the removal of dirt, dust or other debris from a surfaceto be cleaned. For example, the cleaner head may be provided with abrush for sweeping debris from a hard floor surface. As another example,the cleaner head may be provided with a rotatable brush bar comprisingan elongate cylindrical core bearing bristles which extend radiallyoutward from the core. The rotation of the brush bar causes the bristlesto be swept between the fibres of the carpet to be cleaned, agitatingboth the fibres of the carpet and any debris, such as dust particles,fibres and hairs, located on the surface of the carpet and/or betweenthe fibres of the carpet.

It is also known to provide cleaner heads which have a suction openingwhich is bounded on each side by a respective working edge for agitatingthe fibres of a carpeted floor surface as the cleaner head is manoeuvredover such a surface. For example, WO 2002/026097 describes a cleanerhead having a bottom surface which defines a suction opening throughwhich a dirt-bearing air flow is drawn into a suction cavity. The bottomsurface has an inclined leading section extending forwardly from thesuction opening, and which defines a sharp front working edge at itsintersection with a front wall of the suction cavity. The bottom surfacealso has an inclined trailing section extending rearwardly from thesuction opening, and which defines a sharp rear working edge at itsintersection with a rear wall of the suction cavity. With each forwardand reverse stroke of the cleaner head over a carpeted floor surface,air drawn from the atmosphere passes beneath one of these working edgesof the head to enter the suction cavity.

The action of pushing the cleaner head forwardly over the floor surfacecauses the leading section of the bottom surface to be pushed into thefibres of the carpet, concentrating the downward force applied to thecarpet on the front working edge. As the leading section moves over thefibres, the upper ends of the fibres are deflected temporarily in aforwards direction to subsequently spring back into the suction cavity.This rapid movement of the fibres causes dirt and dust to be dislodgedfrom between the fibres and into the suction cavity, where it becomesentrained within the air flow passing beneath the front working edge andinto the suction channel.

A similar action takes place as the cleaner head is pulled rearwardlyover the floor surface; pulling the cleaner head rearwardly over thefloor surface causes the trailing section of the bottom surface to bepulled into the carpet fibres, concentrating the downward force on therear working edge. As the trailing section moves over the fibres, theupper ends of the fibres are deflected temporarily in a rearwarddirection to subsequently spring back into the suction cavity. Dislodgeddirt and dust enters the suction cavity to become entrained within theair flow passing beneath the rear working edge and into the suctionchannel.

The presence of these working edges can increase significantly theefficiency with which dirt and dust is removed from between the fibresof a carpet. To improve the efficiency with which threads, hair and thelike, generally referred to as “lint”, are removed from the surface of acarpet, a thread lifting strip, also referred to as a thread collectingstrip or a lint picker, is located on each of the leading section andthe trailing section of the bottom surface, adjacent the working edgedefined by that section. Each thread lifting strip is generally in theform of a pad adhered or otherwise attached to the cleaner head, andhaving a fibrous lower surface. The fibres of the rear thread liftingstrip are inclined in a common direction to collect lint from the carpetas the cleaner head is moved in a forward direction over the carpet, andto release the collected lint when the cleaner head is pulled rearwardlyover the carpet. The fibres of the front thread lifting strip arealigned in the opposite direction to the fibres of the rear threadlifting strip so as to collected lint as the cleaner head is pulledrearwardly over the carpet, and to release the collected lint when thecleaner head is pushed forwardly over the carpet.

The collected lint tends not to be released immediately from the threadlifting strip; instead the collected lint tends to agglomerate to form amass which is eventually released from the thread lifting strip when itssurface area is sufficiently large as to cause the collected lint to betorn from the thread lifting strip by the air flow passing towards thesuction cavity. Depending on the size of the agglomerated lint, it maynot be able to pass immediately into the suction cavity between thecarpet and the bottom surface of the cleaner head and so may remain onthe floor surface. In this case the user may have to re-position thecleaner head over the released lint so that it can be drawn into thesuction cavity.

When a thread lifting strip is located on a surface that is inclinedtowards the suction opening to define a working edge, that threadlifting strip can tend not to be intimate contact with the carpet acrossits entire width. This can have the effect that the portion of thethread lifting strip located remote from its adjacent working edge canbe less efficient at collecting lint than the portion of the threadlifting strip which is closest to its adjacent working edge. Also, asthe cleaner head is moved forwards and backwards over the floor surfaceby the user, the cleaner head can tend to rock forwards and backwards,alternately raising and lowering the thread lifting strips relative tothe floor surface. As the raising of a thread lifting strip tends tooccur during the stroke in which that thread lifting strip is arrangedto collect lint, the reduced intimacy of the contact between the raisedthread lifting strip and the carpet can further reduce the efficiency ofthe thread lifting strip.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a cleaner head for avacuum cleaning appliance, the cleaner head comprising a suction cavityhaving a downwardly-directed opening through which debris enters thecleaner head, and a thread lifting strip which is moveable relative tothe opening.

As the cleaner head is manoeuvred over a carpet a force is applied in adownwards direction to the carpet by the portions of the cleaner headthat are in contact with the carpet. These portions of the cleaner headmay be support members for supporting the cleaner head as it manoeuvredover the floor. These supports may be in the form of wheels or casters.Alternatively, or additionally, these portions may be in the form of atleast one edge of the opening through which dirt and debris enters thecleaner head.

The contact between the thread lifting strip and the carpet increasesthe surface area of the cleaner head that is in contact with the carpetat any given moment, with the result that the downwards force applied tothe fibres of the carpet by the other features of the cleaner headdecreases. If the thread lifting strip were to be located in a fixedposition relative to the opening, the proportion of the downwards forceapplied to the carpet by the thread lifting strip may becomesufficiently high as to impair the agitation of the fibres of the carpetby, for example, the edges of the opening, through a reduction in theproportion of the force applied to the fibres by these edges, andthereby reduce the performance of the cleaner head for removing dirt anddust trapped between the carpet fibres. In view of this, the threadlifting strip is arranged so as to be moveable relative to the opening.This can reduce the proportion of the downwardly directed force which isapplied to the carpet by the thread lifting strip.

The thread lifting strip may be spaced from the suction cavity. Forexample, the thread lifting strip may be located in front of or behindthe suction cavity. The suction cavity may be formed from a frontsection and a rear section fluidly connected to the front section, andthe thread lifting strip may be located between these sections. Thesuction cavity may therefore extend about the thread lifting strip, butwithout the thread lifting strip being located within the suctioncavity. In these cases, the thread lifting strip is moveable relative toa plane containing the opening.

In a preferred embodiment however, the thread lifting strip is locatedwithin the suction cavity. As the cleaner head is manoeuvred over acarpeted floor surface during use, the reduced air pressure within thesuction cavity causes a portion of the carpet to rise into the suctioncavity to produce a carpet “hill”. The provision of a thread liftingstrip within the suction cavity can enable the thread lifting strip tobe placed in intimate contact with the carpet hill during both forwardsand backwards strokes of the cleaner head over the carpet, increasingthe efficiency of both the collection of lint by the thread liftingstrip and the subsequent release of lint from the thread lifting strip.As the collected lint is released from the thread lifting strip, it isdrawn immediately into the suction cavity, that is, without having topass beneath an edge of the opening or other feature of the lowersurface of the cleaner head. In this case, the thread lifting strip ismoveable towards and away from the opening.

The cleaner head may comprise a single suction cavity. The suctioncavity may comprise a single section arranged to receive air from theopening and to expel air from the suction cavity. Alternatively, thesuction cavity may comprise a front section and a rear section eachhaving a respective opening, with the rear section being arranged toreceive air from the front section, and to expel air from the suctioncavity. In this case, the thread lifting strip may be located in eitherthe front section or the rear section of the suction cavity.

The thread lifting strip may be connected to any surface of the cleanerhead. Where the thread lifting strip is located outside of the suctioncavity, the thread lifting strip may be connected to any externalsurface of the cleaner head, such as the external surface of a bodydefining the suction cavity or the external surface of a hose forconveying air from an outlet of the suction cavity to an outlet of thecleaner head. Alternatively, when it is located beneath the cleanerhead, but external to the suction cavity, the thread lifting strip maybe connected to an internal surface of the cleaner head.

Preferably, the thread lifting strip is connected to a surface locatedwithin the suction cavity. This surface may be part of a wall defining,at least in part, the suction cavity. This surface may be a surface of aside wall of the suction cavity, or the surface of an upper wall of thesuction cavity. The thread lifting strip may extend between two sidewalls of the suction cavity, whereby one end of the thread lifting stripis connected to one side wall and the other end of the thread liftingstrip is connected to the other side wall. Alternatively, the threadlifting strip may be connected to a surface extending across the suctioncavity. This may be in the form of an internal wall or other featurelocated within the suction cavity.

At least part of the thread lifting strip is preferably biased towards aplane containing the opening. This can enable an intimate contact to bemaintained between the thread lifting strip and the carpet with, forexample, any variation in the distance between the upper surface of thecarpet and the plane containing the opening as the cleaner head ismanoeuvred over the carpet.

The thread lifting strip may be biased towards the plane of the openingduring only part of the movement of the cleaner head over a floorsurface. In this case, the thread lifting strip may be moved away fromthe plane of the opening during the other one of a forward stroke or areverse stroke of the cleaner head over the floor surface. For example,a rotatable wheel may be provided on the cleaner head for engaging thefloor surface. The wheel may be connected to a mechanism for moving thethread lifting strip towards or away from the plane of the openingdepending on the rotational direction of the wheel as the cleaner headis manoeuvred over the floor surface.

Alternatively, the thread lifting strip may be biased towards the planeof the opening during both forward and reverse strokes of the cleanerhead over the floor surface. The thread lifting strip may be biasedtowards the plane of the opening in a number of different ways. Asdiscussed above, a thread lifting strip generally comprises an array ofunidirectional fibres disposed on a backing member. This backing membermay be formed from resilient material, such as a metallic, plastics orrubber material. In this case, the attachment of the ends of the threadlifting strip to a surface of the cleaner head, or between two surfacesof the cleaner head, so that at least some of the fibres face the planeof the opening can result in at least those fibres of the thread liftingstrip being urged towards the plane of the opening by the resilientbacking member. Alternatively, the cleaner head may comprise a resilientmember, such as a spring or other elastic member, for engaging thebacking member to urge the fibres of the thread lifting strip towardsthe plane of the opening. This resilient member may be located betweenthe thread lifting strip and a downwardly-facing surface of the cleanerhead, such as the bottom surface of the cleaner head or the uppersurface of the suction cavity. As a further alternative, the threadlifting strip may comprise a plurality of relatively moveable sections.These sections may be hingedly connected, end to end, so that at leastthe centrally disposed sections are urged towards the plane of theopening.

The cleaner head may comprise means for moving the thread lifting striprelative to the opening. The moving means may comprise a support onwhich the thread lifting strip is disposed, and which is moveablerelative to the opening. The thread lifting strip may be mounted on thesupport, for example by using an adhesive to attach a backing member ofthe thread lifting strip to the support. Alternatively, the fibres ofthe thread lifting strip may be disposed directly on the support, forexample using an adhesive. In this case, the adhesive may be consideredto form the backing member of the thread lifting strip.

The support may be biased towards the plane of the opening. The supportmay be biased under its own weight towards the plane of the opening.Alternatively, the support may be formed from resilient material, suchas a metallic, plastics or rubber material.

In a preferred embodiment, resilient means are provided for biasing thesupport towards the plane of the opening. The resilient means maycomprise one or more resilient members, such as springs or other elasticmembers, for engaging the support to urge the thread lifting striptowards the plane of the opening. These resilient members may be locatedbetween the support and a downwardly-facing surface of the cleaner head,such as the bottom surface of the cleaner head or the upper surface ofthe suction cavity. The resilient members may be located outside of thesuction cavity. For example, the support may comprise a rod, shaft orother elongate member which extends through an aperture formed in anupper wall of the suction cavity, and a resilient member, such as atension spring, may be disposed between the end of the elongate memberand the upper wall of the suction cavity to urge the support towards theopening.

Alternatively, the resilient means may be located inside the suctioncavity, and disposed between the support and a surface of the suctioncavity. The resilient means may be provided by one or more elasticmembers. Each of these elastic members may be in the form of a spring,such as a torsion spring or a compression spring, for urging the supportin a direction extending towards the opening, or a flexible connectorfor connecting the support to the suction cavity. This flexibleconnector may be integral with at least one of the support and thesuction cavity.

The support is preferably connected to a cavity wall defining, at leastin part, the suction cavity. This cavity wall may be an upper wall or aside wall of the suction cavity. The support may be connected to thecavity wall for sliding movement relative to, or along the cavity wall.Alternatively, the support may be connected to the cavity wall formovement towards or away from the cavity wall. In one embodiment, thesupport is pivotably connected to the cavity wall. This cavity wall maybe a wall of the suction cavity which defines one of the front edge andthe rear edge of the opening, or it may be a side wall of the suctioncavity.

The support is preferably pivotable about an axis extendingsubstantially parallel to a plane within which the opening is located.The support may comprise at least one arm which extends outwardlytherefrom and which is connected to the cavity wall for movementrelative thereto. At least one of the cavity wall and the support may beshaped to define a channel between the cavity wall and the support sothat the suction cavity surrounds the support. For example, the lengthof the arm(s) connecting the support to the cavity wall may be selectedto space the support from the cavity wall.

One end of the resilient means may be connected to, or engage, thecavity wall and the other end of the resilient means may be connectedto, or engage, the support to urge the support towards the opening.

The cleaner head preferably comprises means for inhibiting threadwrapping around the thread lifting strip. This thread wrappinginhibiting means is preferably located between the support and thecavity wall so that the thread wrapping inhibiting means is at leastpartially located within the channel disposed between the support andthe cavity wall. The thread wrapping inhibiting means thus provides abarrier between the support and the cavity wall which prevents the endsof collected threads or hairs from wrapping around the support beforethey can be released from the thread lifting strip with movement of thecleaner head over the carpet. The thread wrapping inhibiting means ispreferably connected to at least one of the support and the cavity wall.As a first example, the thread wrapping inhibiting means may comprise agrille or mesh which is connected to one of the support and the cavitywall. As a second example, the thread wrapping inhibiting means maycomprise a set of ribs connected to one of the support and the cavitywall and which extend towards the other of the support and the cavitywall. As a third example, the thread wrapping inhibiting means maycomprise a first set of ribs connected to the support and a second setof ribs connected to the cavity wall. Each rib of the first set of ribsis preferably located adjacent to a rib of the second set of ribs.

The thread lifting strip is preferably aligned so as to be substantiallyparallel to the front and rear edges of the opening. The thread liftingstrip may extend partially or substantially fully across the suctioncavity.

The support is preferably moveable relative to the opening between araised position and a lowered position. A stop member is preferablyprovided for inhibiting movement of the stop member beyond the loweredposition. The stop member may be located on the support. The stop membermay be arranged to abut a surface defining, at least in part the suctioncavity, or another surface located within or outside the cavity.

The thread lifting strip is preferably located within a recessed portionof the support. The thread lifting strip is preferably connected to thisrecessed portion of the support using an adhesive. The recessed portionof the support preferably comprises a front edge and a rear edge, eachextending towards the opening, and one of these edges of the supportpreferably extends downwardly beyond the other of these edges. Thethread lifting strip preferably comprises an array of fibres which areinclined towards this one of the edges. This can enable lint which hasaccumulated on the surface of the thread lifting strip to become trappedor “pinched” between this edge and the carpet as the cleaner head ismanoeuvred over the carpet, and this can assist in the removal of theaccumulated lint from the thread lifting strip.

The support is preferably biased towards a position in which said one ofthe edges of the support is substantially co-planar with the front andrear edges of the opening. This prevents this surface from protrudingdownwardly beyond the opening and so prevents the edge from being urgedagainst a hard floor surface on which the cleaner head is located. Inthis position, the lower surface of the thread lifting strip ispreferably substantially parallel to the opening. The stop member ispreferably arranged to contact a wall of the suction cavity to inhibitmovement of the support beyond this position. This wall may be thecavity wall to which the support is connected. This edge of the supportmay be substantially parallel to the front edge and the rear edge of theopening. The edge is preferably relatively sharp, and so the edge ispreferably defined by an edge of a surface, in the form of either aleading or a trailing section of the lower surface of the support, whichis inclined relative to the lower surface of the thread lifting strip.

A plurality of thread lifting strips may be located on the support. Thethread lifting strips may be arranged end to end or in a staggeredarrangement along or on the support, with the fibres of the strips beingaligned in a common direction. Alternatively, the thread lifting stripsmay be arranged in a side by side arrangement, with the fibres of thethread lifting strips being arranged in opposing directions. In thiscase, one thread lifting strip may collect lint during a forward strokeof the cleaner head over a carpet, and the other thread lifting stripmay collect lint during a reverse stroke of the cleaner head over thecarpet. An air channel may be provided between the thread liftingstrips. As a further alternative, the cleaner head may be provided withtwo supports each comprising a respective thread lifting strip.

The cleaner head preferably comprises a bottom surface defining saidopening. The bottom surface preferably has a leading section extendingforwardly from the front edge of the opening and a trailing sectionextending rearwardly from the rear edge of the opening. Each of thesesections is preferably inclined relative to the plane containing theopening to define relatively sharp front and rear edges of the opening.At least one of the leading section of the bottom surface and thetrailing section of the bottom surface may comprise a second threadlifting strip. This second thread lifting strip preferably extendssubstantially the entire width of the cleaner head, and is preferablysubstantially parallel to the front and rear edges of the opening.

In a second aspect, the present invention provides a cleaner head for avacuum cleaning appliance, the cleaner head comprising a suction cavityhaving a downwardly-directed opening through which debris enters thesuction cavity, the opening being bounded in part by a front edge and arear edge, a support located within and moveable relative to the suctioncavity, a thread lifting strip mounted on the support, and resilientmeans for urging the support in a direction extending towards theopening.

Features described above in connection with the first aspect of theinvention are equally applicable to the second aspect of the invention,and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a front perspective view, from above, of a first example of acleaner head;

FIG. 2 is a front perspective view, from below, of the cleaner head ofFIG. 1;

FIG. 3 is a bottom view of the cleaner head of FIG. 1;

FIG. 4 is a front portion of a side cross-section taken along line A-Ain FIG. 3;

FIG. 5 is a front portion of a side cross-sectional view taken alongline B-B in FIG. 3;

FIG. 6 is a front perspective view, from above, of a second example of acleaner head;

FIG. 7 is a front perspective view, from below, of the cleaner head ofFIG. 6;

FIG. 8 is a rear perspective view, from below, of the cleaner head ofFIG. 6;

FIG. 9 is a bottom view of the cleaner head of FIG. 6;

FIG. 10 is a front portion of a side cross-sectional view taken alongline A-A in FIG. 9;

FIG. 11 is a front portion of a side cross-sectional view taken alongline B-B in FIG. 9; and

FIG. 12 is a front portion of a side cross-sectional view taken alongline C-C in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 3 are external views of a first example of a cleaner head 10for a vacuum cleaning appliance. The cleaner head 10 comprises a mainbody 12 and a pair of wheels 14 arranged to allow the cleaner head 10 tobe manoeuvred over a floor surface. Each wheel 14 is rotatably connectedto a respective arm 16 extending rearwardly from the main body 12. Thecleaner head 10 further comprises a connector 18 having an open endwhich is connectable to a wand or hose of a vacuum cleaner.

The main body 12 comprises a lower body section 20 and an upper bodysection 22 extending over and around the lower body section 20. Thelower body section 20 defines a suction cavity of the cleaner head 10.In use, the suction cavity faces the floor surface to be cleaned andadmits dirt-bearing air from the floor surface into the cleaner head 10.

In this example though, the suction cavity comprises a front suctioncavity section 24 and a rear suction cavity section 26. Each suctioncavity section 24, 26 extends substantially fully across the lower bodysection 20. The front suction cavity section 24 is located towards thefront of the main body 12, and the rear suction cavity section 26 islocated towards the rear of the main body 12, behind the front suctioncavity section 24. The front suction cavity section 24 has adownwardly-directed suction opening 28 through which a firstdirt-bearing air flow enters the front suction cavity section 24, andthe rear suction cavity section 26 has a downwardly-directed suctionopening 30 through which a second dirt-bearing air flow enters the rearsuction cavity section 26.

Each of the suction openings 28, 30 is defined by the bottom surface 32of the lower body section 20. The suction opening 28 is delimited byside walls 34, 36, a relatively long front wall 38 and a relatively longrear wall 40 which each upstand from the bottom surface 32 of the lowerbody section 20. A front working edge 42 of the suction opening 28 isdefined at the intersection between the bottom surface 32 and the frontwall 38, and a rear working edge 44 of the suction opening 28 is definedat the intersection between the bottom surface 32 and the rear wall 40.

The suction opening 30 is delimited by side walls 46, 48, a relativelylong front wall 50 and a relatively long rear wall 52 which each alsoupstand from the bottom surface 32 of the lower body section 20. Achannel 54 extending through the main body 12 separates the rear wall 40of the front suction cavity section 24 from the front wall 50 of therear suction cavity section 26. The channel 54 is split into twoportions, with the upper end of each portion of the channel 54 beingopen to the atmosphere. A front working edge 56 of the suction opening30 is defined at the intersection between the bottom surface 32 and thefront wall 50, and a rear working edge 58 of the suction opening 30 isdefined at the intersection between the bottom surface 32 and the rearwall 52.

The working edges 42, 44, 56, 58 are substantially co-planar, locatedwithin a plane P₁, identified in FIG. 4, containing the suction openings28, 30. Each of the working edges 42, 44, 56, 58 is preferably relativesharp, preferably having a radius of curvature less than 0.5 mm. Toprevent the working edges 42, 44, 56, 58 from scratching or otherwisemarking a hard floor surface as the cleaner head 10 is manoeuvred oversuch a surface, the cleaner head 10 comprises surface engaging supportmembers which serve to space the working edges 42, 44, 56, 58 from ahard floor surface. In this embodiment, the cleaner head 10 comprises apair of wheels 60 rotatably mounted within a pair of recesses formed inthe lower body section 20. As shown in FIG. 5, the wheels 60 protrudedownwardly beyond the working edges 42, 44, 56, 58 so that the lowermostextremities of the wheels 60 are disposed beneath the working edges 42,44, 56, 58.

During use, a pressure difference is generated between the air passingthrough the cleaner head 10 and the external environment. This pressuredifference generates a force which acts downwardly on the cleaner head10 towards the floor surface. When the cleaner head 10 is located on acarpeted floor surface, the wheels 60 are pushed into the fibres of thecarpet under the weight of the cleaner head 10 and the force actingdownwardly on the cleaner head 10. The thickness of the wheels 60 isselected so that the wheels 60 will readily sink into the carpet tobring at least the working edges 42, 44, 56, 58 of the main body 12 intocontact with the fibres of the carpet. The thickness of the wheels 60 ispreferably less than 5 mm.

The front suction cavity section 24 is connected to the rear suctioncavity section 26 by intermediate channels 62 which convey the firstdirt-bearing air flow into the rear suction cavity section 26. Eachchannel 62 is located towards a respective side of the main body 12, andpasses beneath part of the bottom surface 32 of the lower body section20. The rear suction cavity section 26 comprises an air outlet 64through which both the first and second dirt-bearing air flows areemitted from the suction cavity. The air flows pass through a flexiblehose 66 supported by the wheels 14 towards the connector 18. One endportion of the hose 66 has a wide mouth that fits over and seals againstthe air outlet 64. The other end of the internal hose 66 has a circularcross-section and is arranged to fit over and seal against a neck 68that, in turns, fits inside the connector 18. The neck 68 is connectedto, preferably integral with, a second pair of arms 70 which extendtowards the main body 12 of the cleaner head 10. Each arm 70 ispivotably connected towards one end thereof to a first end of arespective one of a third pair of arms 72. This provides a firstarticulated joint of the cleaner head 10. The second end of each of thearms 72 is pivotably connected to a respective arm 16 of the main body12 of the cleaner head 10. This provides a second articulated joint ofthe cleaner head 10. The first and second joints pivot about axes thatare parallel to the plane P₁. The connector 18 is arranged to rotatewith respect to the neck 68 about an axis that is orthogonal to the axesof the first and second joints. The rotatable connection of the neck 68with the connector 18 forms a third joint which allows the cleaner head10 to move laterally. In use, the three joints allow the cleaner head 10to be manipulated and steered while maintaining contact of the workingedges 42, 44, 56, 58 with the carpet.

A bleed valve 74 is provided in a cavity 76 located between the lowerbody section 20 and the upper body section 22 of the main body 12. Thecavity 76 has an upper aperture 78 open to the atmosphere and which isdefined by a valve seat. The cavity 76 also has a plurality of lowerapertures 80 in communication with the air outlet 64. The bleed valve 74is biased by a spring 82 into engagement with the valve seat so that,during normal use of the cleaner head 10, there is no air flow throughthe cavity 76. In the event that the suction cavity becomes blocked, forexample, by fabric being drawn into one of the suction cavities 24, 26,the pressure at the air outlet 64 will drop. When the pressure insidethe suction cavity falls below a predetermined value, atmosphericpressure acting on the bleed valve 74 urges it downwardly against theforce of the spring 82, thereby providing a flow path for atmosphericair to enter the cleaner head 10. When the blockage is removed, the airpressure at the air outlet 64 will rise, reducing the force acting onthe bleed valve 74 by the atmospheric air to enable the spring 82 tourge the bleed valve 74 back against the valve seat.

A thread lifting strip support 84 is located in the rear suction cavitysection 26. The support 84 is connected to the lower body section 20 ofthe main body 12 so that it is moveable relative to the lower bodysection 20, and thus relative to the rear suction cavity section 26 andits suction opening 30. In this example, the support 84 is connected tothe front wall 50 of the rear suction cavity section 26. The support 84comprises a pair of arms 86 extending outwardly from a main body of thesupport 84, and which extend through apertures formed in the front wall50. The arms 86 are provided with recesses for receiving shafts 88connected to the front wall 50. The arms 86 are connected to the frontwall 50 in a snap-fit which allows the arms 86 to pivot about an axis Apassing longitudinally through the shafts 88. The length of the arms 86is selected to allow the support 84 to be spaced from the front wall 50so that the rear suction cavity section 26 extends about the main bodyof the support 84.

The main body of the support 84 has a recessed portion 90 to which afirst thread lifting strip 92 is attached, for example using anadhesive. The thread lifting strip 92 is in the form of an elongatestrip or pad, having a lower surface comprising short tufts ofrelatively stiff bristles or fibres. The fibres of the thread liftingstrip 92 are aligned in a common direction, which in this example isinclined downwardly and away from the front wall 50 of the rear suctioncavity section 26. The recessed portion 90 of the support 84 defines,with the lower surface 94 of the support 84, a front edge 96 and a rearedge 98 of the support 84. The rear edge 98 protrudes downwardly beyondthe front edge 96. In a lowered position L of the support, asillustrated in FIGS. 4 and 5, the rear edge 98 is located substantiallyin the plane P₁ containing the working edges 42, 44, 56, 58 of thesuction openings 28, 30. The support 84 includes a stop member 100 whichinhibits movement of the support 84 downwardly beyond this loweredposition L. The stop member 100 is located on one of the arms 86 of thesupport 84, and is arranged to engage an abutment surface 102 located onthe front wall 50 of the rear suction cavity section 26. A similar stopmember 100 may be provided on the other arm 86.

The support 84 can move upwardly from this lowered position L to araised position R, illustrated with dashed lines in FIGS. 4 and 5,through pivoting movement of the support 84 about the axis A. Thesupport 84 is biased towards its lowered position L by a torsion spring104. The torsion spring 104 has a first end which engages the front wall50, and a second end which engages part of the support 84, preferablyone of the arms 86 of the support 84, to urge the support 84 towards itslowered position. A second torsion spring 104 may be provided forengaging the other arm 86 of the support 84.

A second thread lifting strip 106 is attached to the bottom surface 32of the lower body section 20 of the main body 12. In this example, thesecond thread lifting strip 106 is attached to a trailing section 108 ofthe bottom surface. The trailing section 108 extends rearwardly from therear working edge 58 of the suction opening 30, and is inclined upwardlyrelative to the plane P₁ containing the working edges 42, 44, 56, 58.The second thread lifting strip 106 extends substantially the entirewidth of the main body 12. The fibres of the second thread lifting strip106 are aligned so that they are inclined towards the rear working edge58 of the suction opening 30.

In use, the cleaner head 10 is connected to a vacuum cleaning appliancewhich generates a suction airflow. With the cleaner head 10 positionedon a carpeted floor surface to be cleaned, the user sequentially pushesand pulls the wand to move the cleaner head 10 forwards and backwardsover the carpet. During each forward stroke of the cleaner head 10, thefront working edges 42, 56 move over the fibres of the carpet in such adirection that, as the fibres pass beneath the front working edges 42,56 they enter one of the suction cavity sections 24, 26. As these frontworking edges 42, 56 move over the fibres, the upper ends of the fibresare deflected in a forwards direction under the action of a downwardsforce applied by the front working edges 42, 56. Once the front workingedges 42, 56 have moved beyond the deflected fibres, the deflectedfibres spring back into one of the suction cavity sections 24, 26. Thisrapid movement of the fibres causes dirt and dust to be dislodged frombetween the fibres and into the suction cavity sections 24, 26. Dirt anddust entering the front suction cavity section 24 becomes entrainedwithin a first air flow drawn under the front working edge 42 and intothe front suction cavity section 24, whereas dirt and dust entering therear suction cavity section 26 becomes entrained within a second airflow which passes through the channel 54 and under the front workingedge 56 to enter the rear suction cavity section 26. The dirt-bearingfirst air flow passes through the intermediate channels 62 to join thedirt-bearing second air flow within the rear suction cavity section 26.The air flows leave the rear suction cavity section 26 through the airoutlet 64.

During each reverse stroke of the cleaner head 10, the rear workingedges 44, 58 move over the fibres of the carpet in such a directionthat, as the fibres pass beneath the rear working edges 44, 58 theyenter one of the suction cavity sections 24, 26. As the rear workingedges 44, 58 move over the fibres, the upper ends of the fibres aredeflected in a backwards direction under the action of a downwards forceapplied by the rear working edges 44, 58. Once the rear working edges44, 58 have moved over these deflected fibres, the deflected fibresspring back into one of the suction cavity sections 24, 26. This rapidmovement of the fibres causes dirt and dust to be dislodged from betweenthe fibres and into the suction cavity sections 24, 26. Dirt and dustentering the front suction cavity section 24 becomes entrained within afirst air flow which passes through the channel 54 and under the rearworking edge 44 to enter the front suction cavity section 24, whereasdirt and dust entering the rear suction cavity section 26 becomesentrained within a second air flow which is drawn under the rear workingedge 58 and into the rear suction cavity section 26. Again, thedirt-bearing first air flow passes through the intermediate channels 62to join the dirt-bearing second air flow within the rear suction cavitysection 26. The air flows leave the rear suction cavity section 26through the air outlet 64.

Thus, during each of the forwards and backwards strokes of the cleanerhead 10 over the carpet the working edges 42, 44, 56, 58 act to dislodgedirt and debris from between the fibres of the carpet. During each ofthese strokes, the thread lifting strips 92, 106 act to remove lint, inthe form of threads, hair and the like, from the surface of the carpet.As discussed above, the first thread lifting strip 92 is mounted on asupport 84 located within the rear suction cavity section 26. As thecleaner head 10 is manoeuvred over the carpet, a carpet “hill” is pulledinto each of the suction cavity sections 24, 26 as a result of thereduced air pressure within those suction cavity sections 24, 26. Thecarpet hill drawn into the rear suction cavity section 26 engages and isplaced in close contact with the first thread lifting strip 92. As thesupport 84 is moveable relative to the rear suction cavity section 26,the force acting between the carpet and the first thread lifting strip92 as the cleaner head 10 is moved over the carpet is not so great as todiminish significantly the force applied to the carpet fibres by theworking edges 42, 44, 56, 58, while the action of the torsion springs104 maintains the close contact between the carpet and the first threadlifting strip 92.

The fibres of the first thread lifting strip 92 are aligned so that,with each reverse stroke of the cleaner head 10, lint located on thecarpet hill is collected on the surface of the first thread liftingstrip 92. The accumulated lint can be released from the first threadlifting strip 92 with a forward stroke of the cleaner head 10, to becomeentrained within the air flow passing through the rear suction cavitysection 26. The release of the collected lint from the first threadlifting strip 92 can be assisted by the rear support edge 98; as thecleaner head 10 is moved in a forward direction the collected lint canbecome trapped or pinched between the rear support edge 98 and thecarpet, and this can result in the collected lint being torn from thefirst thread lifting strip to become entrained within the air flowpassing through the rear suction cavity section 26.

The fibres of the second thread lifting strip 106 are aligned so that,with each forward stroke of the cleaner head 10, lint located on thecarpet directly behind the rear suction cavity section 26 can becomecollected on the surface of the second thread lifting strip 106. Theaccumulated lint can be released from the second thread lifting strip106 with a reverse stroke of the cleaner head 10. This released lint caneither become entrained within the second air flow passing beneath therear working edge 58 of the rear suction cavity section 26, or remain onthe surface of the carpet to be subsequently drawn into the cleaner head10.

FIGS. 6 to 9 are external views of a second example of a cleaner head110 for a vacuum cleaning appliance. Similar to the first example, thecleaner head 110 comprises a main body 112 and a pair of wheels 114arranged to allow the cleaner head 110 to be manoeuvred over a floorsurface. The main body 112 comprises a lower body section 116 pivotablyconnected to an upper body section. The upper body section comprises afront section 118 to which the lower body section 116 is connected, anda rear section 120 pivotably connected to the front section 118. Thewheels 114 are connected to the rear section 120 of the main body 112.The rear section 120 comprises a connector 122 having an open end whichis connectable to a wand or hose of a vacuum cleaner.

In this second example, the lower body section 116 defines a singlesuction cavity 124 of the cleaner head 110. In use, the suction cavityfaces the floor surface to be cleaned and admits dirt-bearing air fromthe floor surface into the cleaner head 110. The suction cavity 124extends substantially fully across the lower body section 116. Thesuction cavity 124 has a downwardly-directed suction opening 126 throughwhich a dirt-bearing air flow enters the suction cavity 124. The suctionopening 126 is defined by the bottom surface of the lower body section116. The suction opening 126 is delimited by a relatively long frontwall 128, a relatively long rear wall 130, and two relatively short sidewalls 132, 134 which extend between the ends of the relatively longwalls 128, 130. A front working edge 136 of the suction opening 126 isdefined at the intersection between the bottom surface of the lower bodysection 116 and the front wall 128, and a rear working edge 138 of thesuction opening 126 is defined at the intersection between the bottomsurface and the rear wall 130. The working edges 136, 138 aresubstantially co-planar and located within a plane containing thesuction opening 126. The suction cavity 124 comprises a centrallylocated air outlet 140 which conveys a dirt-bearing air flow into an airpassageway 142 extending through the lower body section 116. The upperbody section comprises a conduit 144 for conveying the dirt-bearing airflow from the air passageway 142 to the connector 122.

In this second example, the cleaner head 110 comprises a frame or cover146 extending over and around the lower body section 116. The frame 146bears a set of bristles 148 which extend downwardly around the lowerperiphery of the lower body section 116. The cleaner head 110 comprisesa mechanism 150 for allowing the user to move the frame 146 between alowered position, as illustrated in FIGS. 6 to 12, in which the lowerends of the bristles are located beneath the plane containing thesuction opening 126, and a raised position in which the lower ends ofthe bristles are located beneath this plane. When the frame 146 is inits lowered position, the cleaner head 110 is in a configuration forcleaning a hard floor surface. The working edges 136, 138 are spacedfrom the hard floor surface to prevent those edges from scratching orotherwise marking the hard floor surface. When the frame 146 is in itsraised position, the cleaner head 110 is in a configuration for cleaninga carpeted surface, as the working edges 136, 138 may be brought intocontact with the fibres of the carpet.

A thread lifting strip support 152 is located in the suction cavity 124.The support 152 is connected to the lower body section 116 of the mainbody 112 so that it is moveable relative to the lower body section 116,and thus relative to the suction cavity 124 and the suction opening 126.In this second example, the support 152 is connected to the front wall128 of the suction cavity 124. With reference also to FIG. 10, thesupport 152 comprises a pair of arms 154 each extending outwardly from arespective end of a main body of the support 152, and which extendthrough apertures formed in the front wall 128. The arms 154 areprovided with recesses for receiving shafts 156 connected to the frontwall 128. The arms 154 are connected to the front wall 128 in a snap-fitwhich allows the arms 154 to pivot about an axis passing longitudinallythrough the shafts 156 and which is parallel to the plane of the suctionopening 126. The length of the arms 154 is selected to allow the support152 to be spaced from the front wall 128 so that the suction cavity 124extends about the main body of the support 152.

As in the first example, the main body of the support 152 has a recessedportion 158 to which a first thread lifting strip 160 is attached, forexample using an adhesive. The thread lifting strip 160 is in the formof an elongate strip or pad, having a lower surface comprising shorttufts of relatively stiff bristles or fibres. The fibres of the threadlifting strip 160 are aligned in a common direction, which in thisexample is inclined downwardly and away from the front wall 128 of thesuction cavity 124. The recessed portion 158 of the support 152 defines,with the lower surface of the support 152, a front edge 162 and a rearedge 164 of the support 152. The rear edge 164 protrudes downwardlybeyond the front edge 162. In this second example, in a lowered positionof the support 152, as illustrated in FIGS. 10 to 12, the rear edge 164is located above the plane of the suction opening 126. The support 152includes a stop member 166 which inhibits movement of the support 152downwardly beyond this lowered position. The stop member 166 is locatedon the main body of the support 152, and is arranged to engage the frontwall 128 of the suction cavity 124.

As in the first example, the support 152 can move upwardly from thislowered position to a raised position through pivoting movement of thesupport 152 relative to the front wall 128 of the suction cavity 124.The support 152 is biased towards its lowered position by a torsionspring 168. The torsion spring 168 has a first end which engages thefront wall 128, and a second end which engages part of the support 152,preferably one of the arms 154 of the support 152, to urge the support152 towards its lowered position. A second torsion spring may beprovided for engaging the other arm 154 of the support 152.

In this second example, the cleaner head 110 includes means forinhibiting the wrapping of threads or hair around the support 152, inparticular threads or hairs which have been collected in such anorientation that their length extends generally along the thread liftingstrip 160. The means for inhibiting the wrapping of threads or hairaround the support 152 is located in a channel 170 extending between thefront wall 128 and the main body of the support 152. In this example,the means for inhibiting the wrapping of threads or hair around thesupport 152 comprise a first set of ribs 172 connected to the support152 and which extend into the channel 170 towards the front wall 128,and a second set of ribs 174 connected to the front wall 150 and whichextend into the channel 170 towards the support 152. Each rib of thefirst set of ribs 172 is preferably located adjacent to one of the ribsof the second set of ribs 174. The ribs provide a barrier along one sideof the support 152 which prevents the ends of threads captured by thethread lifting strip 160 from wrapping around the support 152 withoutimpeding significantly the flow of air through the channel 170 towardsthe outlet of the suction cavity 124.

A second thread lifting strip 176 is attached to the bottom surface ofthe lower body section 116 of the main body 112. In this example, thesecond thread lifting strip 176 is attached to a trailing section of thebottom surface. The trailing section extends rearwardly from the rearworking edge 138 of the suction opening 126, and is inclined upwardlyrelative to the plane containing the working edges 136, 138. The secondthread lifting strip 176 extends substantially the entire width of themain body 112. The fibres of the second thread lifting strip 176 arealigned so that they are inclined towards the rear working edge 138.

In use, the operation of the cleaner head 110 for cleaning a carpetedfloor surface, and so when the frame 146 is in its raised position, issimilar to that of the cleaner head 10. During each forward stroke ofthe cleaner head 110, the front working edge 136 agitates the fibres ofthe carpet to cause dirt and dust to be dislodged from between thefibres and into the suction cavity 124. This dirt and dust becomesentrained within an air flow drawn under the front working edge 136 intothe suction cavity 124. During each reverse stroke of the cleaner head110, the rear working edge 138 agitates the carpet fibres to dislodgedirt and dust from between the carpet fibres and into the suction cavity124. This dirt and dust becomes entrained within an air flow drawn underthe rear working edge 138 and into the suction cavity 124. Thedirt-bearing air flow leaves the suction cavity 124 through the airoutlet 140, and passes through the cleaner head 110 to the wand or hoseof a vacuum cleaner attached to the connector 122.

During each of these strokes, the thread lifting strips 160, 176 act toremove lint, in the form of threads, hair and the like, from the surfaceof the carpet. As discussed above, the first thread lifting strip 160 ismounted on a support 152 located within the suction cavity 124. As thecleaner head 110 is manoeuvred over the carpet, a carpet “hill” ispulled into the suction cavity 124 as a result of the reduced airpressure within the suction cavity 124. The carpet hill engages and isplaced in close contact with the first thread lifting strip 160. As thesupport 152 is moveable relative to the suction cavity 124, the forceacting between the carpet and the first thread lifting strip 160 as thecleaner head 110 is moved over the carpet is not so great as to diminishsignificantly the force applied to the carpet fibres by the workingedges 136, 138, while the action of the torsion spring 168 maintains theclose contact between the carpet and the first thread lifting strip 160.

The fibres of the first thread lifting strip 160 are aligned so that,with each reverse stroke of the cleaner head 110, lint located on thecarpet hill is collected on the surface of the first thread liftingstrip 160. The accumulated lint can be released from the first threadlifting strip 160 with a forward stroke of the cleaner head 10, tobecome entrained within the air flow passing through the suction cavity124. The release of the collected lint from the first thread liftingstrip 160 can be assisted by the rear support edge 164; as the cleanerhead 110 is moved in a forward direction the collected lint can becometrapped or pinched between the rear support edge 164 and the carpet, andthis can result in the collected lint being torn from the first threadlifting strip 160 to become entrained within the air flow passingthrough the suction cavity 124.

The fibres of the second thread lifting strip 176 are aligned so that,with each forward stroke of the cleaner head 10, lint located on thecarpet directly behind the suction cavity 124 can become collected onthe surface of the second thread lifting strip 176. The accumulated lintcan be released from the second thread lifting strip 176 with a reversestroke of the cleaner head 110. This released lint can either becomeentrained within the air flow passing beneath the rear working edge 138,or remain on the surface of the carpet to be subsequently drawn into thecleaner head 110.

1. A cleaner head for a vacuum cleaning appliance, the cleaner headcomprising: a suction cavity having a downwardly-directed openingthrough which debris enters the cleaner head; and a thread lifting striplocated within the suction cavity and which is moveable relative to theopening.
 2. The cleaner head of claim 1, wherein the thread liftingstrip is moveable relative to a plane containing the opening.
 3. Thecleaner head of claim 1, wherein the thread lifting strip is moveabletowards and away from the opening.
 4. The cleaner head of claim 1,wherein the thread lifting strip is connected to a surface of a wall ofthe cleaner head.
 5. The cleaner head of claim 4, wherein the surface islocated within the suction cavity.
 6. The cleaner head of claim 1,wherein the suction cavity surrounds the thread lifting strip.
 7. Thecleaner head of claim 1, wherein the thread lifting strip is biasedtowards a plane containing the opening.
 8. The cleaner head of claim 1,wherein the thread lifting strip is moveable relative to the opening. 9.The cleaner head of claim 8, comprising a support on which the threadlifting strip is disposed, and wherein the support is moveable relativeto the opening.
 10. The cleaner head of claim 9, wherein the support isbiased towards a plane containing the opening.
 11. The cleaner head ofclaim 9, comprising at least one resilient member for urging the supporttowards a plane containing the opening.
 12. The cleaner head of claim11, wherein the at least one resilient member comprises at least onetorsion spring.
 13. The cleaner head of claim 9, wherein the threadlifting strip is mounted on the support.
 14. The cleaner head of claim9, wherein the support is connected to a cavity wall defining, at leastin part, the suction cavity.
 15. The cleaner head of claim 14, whereinthe support is pivotably connected to the cavity wall.
 16. The cleanerhead of claim 15, wherein the support is pivotable about an axisextending substantially parallel to a plane containing the opening. 17.The cleaner head of claim 14, wherein the cavity wall defines one of afront edge and a rear edge of the opening.
 18. The cleaner head of claim14, wherein the support comprises at least one arm which extendsoutwardly therefrom and which is connected to the cavity wall formovement relative thereto.
 19. The cleaner head of claim 9, wherein thesupport is moveable between a raised position and a lowered position,and the cleaner head comprises a stop member for inhibiting movement ofthe support beyond the lowered position.
 20. The cleaner head of claim19, wherein the support comprises said stop member.
 21. The cleaner headof claim 19, wherein the stop member is arranged to abut a surfacedefining, at least in part, said suction cavity.
 22. The cleaner head ofclaim 19, wherein the thread lifting strip is located within a recessedportion of the support.
 23. The cleaner head of claim 22, wherein therecessed portion of the support comprises a front support edge and arear support edge, and wherein the edges do not extend downwardly beyonda plane containing the opening when the support is in its loweredposition.
 24. The cleaner head of claim 23, wherein one of the supportedges protrudes further from the support than the other support edge.